Hair dyeing conventionally includes the use of a rectangular aluminum foil or other plastic material, as a flat support for a lock of hair to be selectively colored, as means to enclose the lock by the folding in two of the aluminum foil in view of enclosing and containing the bleach or dye fluid applied to the lock, and as a compression pad to maintain the dye fluid over each hair strand of the lock. The foil is usually positioned transversely of the scalp to edgewisely abut against the scalp. Thus, substantially all the length of each hair strand of that lock will come in contact with the dye fluid. Such a technique of selective coloring of a lock is known in the trade as hair highlighting.
Since the dye fluid, which may consist of a gel, or cream, usually includes a liquid coloring ingredient combined with an oxidizer, usually peroxide (H.sub.2 O.sub.2), it is desirable to prevent the dye fluid from engaging the scalp. Therefore, because of the high flexibility of the rectangular aluminum sheet material, each of the two opposite pairs of overlapping lateral side edge portions of the folded sheet must be edgewisely folded onto themselves, to "close" both lateral side edges of the folded sheet. This is required, because additional structural rigidity to the folded sheet must be provided, dye leakage must be prevented, and each colored lock must be isolated from the remaining hair. This edgewise folding is also required because aluminum has a somewhat slippery surface, therefore the aluminum foil would otherwise slip and slide off the hair during the hour-long development time.